Many recently developed pharmaceuticals are therapeutic proteins. Therapeutic protein products were not routinely administered to patients until molecular biology techniques had evolved to allow production of the protein recombinantly. Therapeutic proteins are typically from a mammal, e.g., a human, and are generally produced in cultured cells derived from multicellular eukaryotic organisms, e.g., Chinese hamster ovary cells or other mammalian cells. Such mammalian cell production methods are expensive and time consuming, but are believed to allow for optimal post-translational processing of the recombinant protein. Post-translational processing includes, e.g., refolding and formation of correct disulfide bonds and glycosylation of the protein. Microorganisms are an attractive substitute for eukaryotic cells, but have not been successfully used to produce commercial scale amounts of therapeutic proteins. Microorganisms, in particular E. coli, do not promote post-translational processing of eukaryotic proteins. For example, many eukaryotic proteins, including many therapeutic proteins are expressed as insoluble inclusion bodies in microorganisms, including E. coli. Thus, there is a need for improved methods to produce active therapeutic proteins in microorganisms. The present invention solves this and other needs.